Two-stage variable pressure nitrogen gas spring
By designing a two-stage variable pressure nitrogen spring, the elastic force is changed in two stages, which solves the problem of mold closing force release in deep drawing forming parts, reduces mold design cost, improves process formability, and stabilizes piston rod reset. It is suitable for deep drawing forming process of stamping dies.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- TANGXIA BRANCH VISION TOOL & MOLD
- Filing Date
- 2025-07-18
- Publication Date
- 2026-07-14
AI Technical Summary
Existing nitrogen springs cannot meet the mold closing force release requirements of deep drawing parts in stamping processes, resulting in high mold design costs and space occupation. Furthermore, the relationship between elastic force and displacement movement is simplistic, limiting the process formability.
Design a two-stage variable pressure nitrogen spring. The inner cavity is divided into upper and lower chambers by a piston. The two-stage change of spring force is achieved by using an upward overflow valve and a flow control valve. The working pressure area is changed by combining different stroke areas of the piston rod to achieve switching between high and low spring force.
It effectively meets the elasticity requirements of different displacement strokes, and is especially suitable for deep drawing forming processes. It reduces mold design costs, improves process formability, and stabilizes piston rod reset through flow control, reducing impact force.
Smart Images
Figure CN224497210U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of nitrogen spring technology, and in particular to a two-stage variable pressure nitrogen spring. Background Technology
[0002] In stamping dies, nitrogen springs play a crucial role in the formability and precision of stamped parts. Nitrogen springs are lightweight, have a long service life, adjustable spring force and stroke, are easy to assemble, and are easy to maintain. Currently used nitrogen springs are similar to metal springs, following the working principle that the spring force gradually increases with the compression stroke.
[0003] Conventional stamping processes require a constant clamping force. Existing nitrogen springs can meet this requirement. However, for deep-drawn parts, to increase metal flow into the die cavity, the clamping force needs to be released at a certain point—that is, a smaller clamping force is required. This allows metal at the blank holder to flow more easily into the die cavity, resulting in better processability of the sheet metal. Currently, meeting this forming process requirement can only be achieved using servo mechanisms, which not only increases mold production costs but also occupies production space. This is a difficult process problem currently encountered in mold design.
[0004] Furthermore, the relationship between the elastic force and displacement of nitrogen springs in existing technology is a single linear relationship. If independent nitrogen springs could be designed with variable pressure mechanical operation capabilities similar to unloading functions, it would greatly expand the design space of stamping processes and effectively improve the formability of sheet metal, especially for mold design involved in deep rolling processes. Therefore, the shortcomings are quite obvious, and a solution is urgently needed. Utility Model Content
[0005] In order to solve the above-mentioned technical problems, the purpose of this utility model is to provide a two-stage variable pressure nitrogen spring.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A two-stage variable pressure nitrogen spring includes a housing, a piston rod, a piston, a flow control valve, an upward overflow valve, and a downward overflow valve. The housing has an inner cavity and a through hole communicating with the top of the inner cavity. A piston sleeve is embedded in the through hole. The piston rod slides through the piston sleeve. The piston is mounted at the bottom end of the piston rod and is vertically positioned within the inner cavity. A first sealing ring is embedded in the peripheral wall of the piston. The piston is slidably connected to the inner wall of the inner cavity via the first sealing ring. The flow control valve, the upward overflow valve, and the downward overflow valve are all axially embedded in the piston. An inflation valve is embedded in the bottom of the housing. A buffer pad is provided on the inner top wall of the inner cavity. The top surface of the piston can abut against the buffer pad. The piston rod slides through the buffer pad. The piston can divide the inner cavity into an upper cavity and a lower cavity. The inflation valve communicates with the lower cavity of the inner cavity. The inlet of the downward overflow valve communicates with the upper cavity of the inner cavity. The outlet of the downward overflow valve communicates with the lower cavity of the inner cavity via the flow control valve.
[0008] Furthermore, there are two upward overflow valves, which are symmetrically arranged on the piston.
[0009] Furthermore, a first guide ring is embedded in the peripheral wall of the piston, and the first guide ring is slidably connected to the inner wall of the inner cavity.
[0010] Furthermore, the number of first sealing rings is at least two, and the first guide ring is located between two adjacent first sealing rings.
[0011] Furthermore, a second sealing ring is embedded in the inner wall of the piston sleeve, and the outer wall of the piston rod is in a sealing sliding connection with the inner wall of the second sealing ring.
[0012] Furthermore, a second guide ring is embedded in the inner wall of the piston sleeve, and the inner wall of the second guide ring is slidably connected to the outer wall of the piston rod. The second guide ring is located below the second sealing ring.
[0013] Furthermore, a dustproof ring is embedded in the inner wall of the piston sleeve, and the inner wall of the dustproof ring slides against the outer wall of the piston rod. The second sealing ring is located between the dustproof ring and the second guide ring.
[0014] Furthermore, the piston is provided with multiple mounting holes, and the flow control valve, the upward overflow valve and the downward overflow valve are respectively mounted in the corresponding mounting holes.
[0015] Furthermore, a cover plate is installed on the bottom surface of the piston, and the cover plate has several through holes. The outlet of the flow control valve and the inlet of the upward overflow valve are respectively connected to the corresponding through holes.
[0016] Furthermore, a top cover is detachably installed at the top port of the housing, through which the piston rod slides, and the top cover encapsulates the piston sleeve within the through hole.
[0017] The beneficial effects of this utility model are as follows: In practical applications, nitrogen is injected into the inner cavity through the inflation valve, gradually increasing the amount of nitrogen in the inner cavity and gradually pushing the piston upward until the top surface of the piston contacts the buffer pad, and the gas pressure in the lower cavity reaches the preset gas pressure value. When the top of the piston rod is subjected to a downward force, and this downward force is greater than the pressure of the nitrogen, the piston rod, along with the piston, moves downward along the inner cavity and compresses the nitrogen in the inner cavity, so that the piston divides the inner cavity into an upper cavity and a lower cavity. As the downward stroke of the piston increases, the nitrogen pressure in the lower cavity of the inner cavity gradually increases. This process is the first stage, and the force-displacement relationship in the first stage is a stage of gradually increasing high elasticity. When the nitrogen pressure in the lower cavity of the inner cavity reaches the pressure value set by the upward overflow valve, the valve core of the upward overflow valve opens, and the compressed nitrogen flows out. The lower chamber enters the upper chamber, and the gas pressure in the upper chamber is equal to that in the lower chamber. As the piston rod and piston continue to move downward, the second stage begins. Since the upper and lower chambers contain nitrogen at the same pressure, the upper and lower sides of the piston's outer ring area Sa bear the same nitrogen pressure. The piston's working area is only the central area Sb corresponding to the piston rod. In other words, the piston's working area decreases, and the corresponding elastic force also decreases. The larger the piston's outer ring area Sa is, the greater the decrease in elastic force, causing the elastic force in the second stage to decrease dramatically compared to the elastic force in the first stage. The piston rod and piston continue to move downward in this state, and the nitrogen pressure in the lower chamber of the inner cavity will still gradually increase. The force and displacement relationship in the second stage is that the low elastic force gradually increases to achieve a two-stage (stepped) elastic force change. When the piston rod and piston need to reset, the downward overflow valve is activated, releasing the force applied to the top of the piston rod. The piston moves upward along the inner cavity, driving the piston rod upward. As the piston moves upward, the nitrogen in the upper cavity flows back to the lower cavity through the downward overflow valve until the top surface of the piston contacts the buffer pad, allowing all the nitrogen in the upper cavity to flow back to the lower cavity. When the piston and piston rod move upward to reset, the flow rate of the gas is controlled by the flow control valve to control the reset speed of the piston and piston rod, thereby controlling the impact force generated by the piston and piston rod reset. This invention features a two-stage elastic force variation, transitioning from a high elastic force gradually increasing stage to a low elastic force gradually increasing stage. This expands the single linear variation of elastic force in existing technologies into a two-stage linear variation, satisfying the need for different linear elastic force variations required for different displacement strokes. It can effectively meet the design requirements of special stamping forming processes, and is particularly suitable for deep drawing forming processes of stamping dies. Furthermore, when the piston rod moves upward and resets, the flow rate of the gas return is controlled by a flow control valve, effectively controlling the impact force generated by the piston rod, making the reset of the piston rod more stable. Attached Figure Description
[0018] Figure 1 This is a cross-sectional view of the present invention.
[0019] Figure 2 This is a schematic diagram of the working area of the piston of this utility model.
[0020] Figure 3 This is a schematic diagram illustrating the force and displacement relationship in two stages of this invention.
[0021] Explanation of reference numerals in the attached figures:
[0022] 1. Housing; 2. Piston rod; 3. Piston; 4. Flow control valve; 5. Upward overflow valve; 6. Downward overflow valve; 7. Inner cavity; 8. Through hole; 9. Piston sleeve; 10. First sealing ring; 11. Inflation valve; 12. Buffer pad; 13. First guide ring; 14. Second guide ring; 15. Second sealing ring; 16. Dustproof ring; 17. Mounting hole; 18. Cover plate; 19. Through hole; 20. Top cover. Detailed Implementation
[0023] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.
[0024] like Figures 1 to 3 As shown, this utility model provides a two-stage variable pressure nitrogen spring, which includes a housing 1, a piston rod 2, a piston 3, a flow control valve 4, an upward overflow valve 5, and a downward overflow valve 6. The housing 1 is provided with an inner cavity 7 and a through hole 8 communicating with the top of the inner cavity 7. A piston sleeve 9 is embedded in the through hole 8. The piston rod 2 slides through the piston sleeve 9. The piston 3 is installed at the bottom end of the piston rod 2 and is raised and lowered in the inner cavity 7. A first sealing ring 10 is embedded on the periphery of the piston 3. The piston 3 is slidably connected to the inner wall of the inner cavity 7 in a sealing manner through the first sealing ring 10. The flow control valve 4, the upward overflow valve 5, and the downward overflow valve 6 are all provided. Both the upper overflow valve 5 and the lower overflow valve 6 are axially embedded in the piston 3. An inflation valve 11 is embedded in the bottom of the housing 1. The piston 3 is located above the inflation valve 11. A buffer pad 12 is provided on the inner top wall of the inner cavity 7. The top surface of the piston 3 can abut against the buffer pad 12. The piston rod 2 slides through the buffer pad 12. The piston 3 can divide the inner cavity 7 into an upper cavity and a lower cavity. The inflation valve 11 is connected to the lower cavity of the inner cavity 7. The air inlet of the lower overflow valve 6 is used to communicate with the upper cavity of the inner cavity 7. The air outlet of the lower overflow valve 6 is connected to the lower cavity of the inner cavity 7 through the flow control valve 4.
[0025] In practical applications, nitrogen is injected into the inner cavity 7 through the inflation valve 11, gradually increasing the amount of nitrogen in the inner cavity 7 and gradually pushing the piston 3 upward until the top surface of the piston 3 contacts the buffer pad 12, and the gas pressure in the lower cavity reaches the preset gas pressure value. When the top of the piston rod 2 is subjected to a downward force, and this downward force is greater than the pressure of the nitrogen, the piston rod 2, together with the piston 3, moves downward along the inner cavity 7 and compresses the nitrogen in the inner cavity 7, so that the piston 3 divides the inner cavity 7 into an upper cavity and a lower cavity. As the downward stroke of the piston 3 increases, the nitrogen pressure in the lower cavity of the inner cavity 7 gradually increases. This process is the first stage, and the force-displacement relationship in the first stage is a stage of gradually increasing high elasticity. When the nitrogen pressure in the lower cavity of the inner cavity 7 reaches the pressure value set by the upward overflow valve 5, the valve core of the upward overflow valve 5 opens, and the compressed nitrogen flows out from the upper cavity 7. The lower chamber enters the upper chamber, and the air pressure in the upper chamber is equal to that in the lower chamber. As piston rod 2 and piston 3 continue to move downward, the second stage begins. Since the upper and lower chambers contain nitrogen at the same pressure, the upper and lower sides of the outer ring area Sa of piston 3 bear the same nitrogen pressure. The working area of piston 3 is only the central area Sb corresponding to piston rod 2. That is, the working area of piston 3 decreases, and the elastic force it provides also decreases. The larger the outer ring area Sa of piston 3 is, the greater the decrease in elastic force, so that the elastic force in the second stage is significantly reduced compared to the elastic force in the first stage. In this state, piston rod 2 and piston 3 continue to move downward, and the nitrogen pressure in the lower chamber of inner cavity 7 will still gradually increase. The force and displacement relationship in the second stage is that the low elastic force gradually increases to achieve a two-stage (stepped) elastic force change. When piston rod 2 and piston 3 need to reset, the downward overflow valve 6 is activated, releasing the force applied to the top of piston rod 2. Piston 3 will move upward along the inner cavity 7, and piston 3 will drive piston rod 2 to move upward. As piston 3 moves upward, nitrogen in the upper cavity flows back to the lower cavity through the downward overflow valve 6 until the top surface of piston 3 contacts the buffer pad 12, so that all nitrogen in the upper cavity flows back to the lower cavity. When piston 3 and piston rod 2 move upward to reset, the flow rate of gas is controlled by the flow control valve 4 to control the reset speed of piston 3 and piston rod 2, thereby controlling the impact force generated by the reset of piston 3 and piston rod 2. This invention features a two-stage elastic force variation, transitioning from a high elastic force gradually increasing stage to a low elastic force gradually increasing stage. This expands the single linear variation of elastic force in the prior art into a two-stage linear variation, satisfying the need for different linear variations of elastic force required for different displacement strokes. It can effectively meet the design requirements of special stamping forming processes, and is particularly suitable for deep drawing forming processes of stamping dies. Furthermore, when the piston rod 2 moves upward and resets, the flow rate of the gas return is controlled by the flow control valve 4, effectively controlling the impact force generated by the piston rod 2, making the reset of the piston rod 2 more stable.
[0026] It should be noted that the high elasticity and low elasticity in this embodiment refer to a comparison of elasticity in two stages.
[0027] In this embodiment, there are two upward overflow valves 5, which are symmetrically arranged on the piston 3. The nitrogen gas in the lower chamber is introduced into the upper chamber through the two symmetrical upward overflow valves 5, so that the piston 3 is subjected to uniform force and the force deviation caused by gas flow can be balanced.
[0028] In this embodiment, a first guide ring 13 is embedded in the peripheral sidewall of the piston 3, and the first guide ring 13 is slidably connected to the inner sidewall of the inner cavity 7. The first guide ring 13 makes the piston 3 move more stably and smoothly in the inner cavity 7.
[0029] In this embodiment, there are at least two first sealing rings 10, and the first guide ring 13 is located between two adjacent first sealing rings 10; this structure design has good sealing performance and will not cause air leakage.
[0030] In this embodiment, a second sealing ring 15 is embedded in the inner wall of the piston sleeve 9, and the outer wall of the piston rod 2 is slidably connected to the inner wall of the second sealing ring 15. This structural design improves the sealing performance between the piston sleeve 9 and the piston rod 2.
[0031] In this embodiment, a second guide ring 14 is embedded in the inner wall of the piston sleeve 9. The inner wall of the second guide ring 14 is slidably connected to the outer wall of the piston rod 2, and the second guide ring 14 is located below the second sealing ring 15. This structural design makes the movement of the piston rod 2 smoother and more stable.
[0032] In this embodiment, a dustproof ring 16 is embedded in the inner wall of the piston sleeve 9. The inner wall of the dustproof ring 16 slides against the outer wall of the piston rod 2. The second sealing ring 15 is located between the dustproof ring 16 and the second guide ring 14. The dustproof ring 16 serves to prevent dust.
[0033] In this embodiment, the piston 3 is provided with multiple mounting holes 17, and the flow control valve 4, the upward overflow valve 5, and the downward overflow valve 6 are respectively mounted in the corresponding mounting holes 17. This structural design facilitates the assembly and disassembly of the flow control valve 4, the upward overflow valve 5, and the downward overflow valve 6.
[0034] In this embodiment, a cover plate 18 is installed on the bottom surface of the piston 3. The cover plate 18 has several through holes 19, and the outlet of the flow control valve 4 and the inlet of the upward overflow valve 5 are respectively connected to the corresponding through holes 19. The cover plate 18 limits the flow control valve 4, the upward overflow valve 5 and the downward overflow valve 6 within the mounting hole 17, so that the flow control valve 4, the upward overflow valve 5 and the downward overflow valve 6 can be firmly installed in the mounting hole 17 of the piston 3.
[0035] In this embodiment, a top cover 20 is detachably installed at the top port of the housing 1, and the piston rod 2 slides through the top cover 20, with the top cover 20 encapsulating the piston sleeve 9 within the through hole 8. This structural design facilitates the assembly and disassembly of the piston sleeve 9.
[0036] In order to change the single elastic force and displacement relationship of nitrogen springs in the prior art and reduce mold design costs, this application provides a technical solution that can change the working pressure area of piston 3. That is, the working pressure area of piston 3 is different in different stroke regions, thereby realizing the change of elastic force, thereby meeting the stamping forming process design requirements of mold.
[0037] In addition, the return impact state of the piston rod 2 in this application is adjustable. That is, by controlling the flow of nitrogen gas through the mutual flow process of the two spaces (upper chamber and lower chamber), the compression and release state of nitrogen gas can be realized, thereby changing the release impact characteristics and providing a more stable and slower return force.
[0038] All technical features in this embodiment can be freely combined according to actual needs.
[0039] The above embodiments are preferred implementations of this utility model. In addition, this utility model can also be implemented in other ways. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this utility model.
Claims
1. A two-stage variable pressure nitrogen spring, characterized in that: The system includes a housing (1), a piston rod (2), a piston (3), a flow control valve (4), an upward overflow valve (5), and a downward overflow valve (6). The housing (1) has an inner cavity (7) and a through hole (8) communicating with the top of the inner cavity (7). A piston sleeve (9) is embedded in the through hole (8). The piston rod (2) slides through the piston sleeve (9). The piston (3) is installed at the bottom end of the piston rod (2) and is raised and lowered in the inner cavity (7). A first sealing ring (10) is embedded in the peripheral wall of the piston (3). The piston (3) is slidably connected to the inner wall of the inner cavity (7) through the first sealing ring (10). The flow control valve (4), upward overflow valve (5), and downward overflow valve (6) are connected to the piston rod (2), piston (3), piston (4), piston rod (2), piston (3), flow control valve (4), upward overflow valve (5), and downward overflow valve (6). Both the overflow valve (5) and the downward overflow valve (6) are axially embedded in the piston (3). The bottom of the housing (1) is fitted with an inflation valve (11). The inner top wall of the inner cavity (7) is provided with a buffer pad (12). The top surface of the piston (3) can abut against the buffer pad (12). The piston rod (2) slides through the buffer pad (12). The piston (3) can divide the inner cavity (7) into an upper cavity and a lower cavity. The inflation valve (11) is connected to the lower cavity of the inner cavity (7). The air inlet of the downward overflow valve (6) is used to communicate with the upper cavity of the inner cavity (7). The air outlet of the downward overflow valve (6) is connected to the lower cavity of the inner cavity (7) through the flow control valve (4).
2. The two-stage variable pressure nitrogen spring according to claim 1, characterized in that: There are two upward overflow valves (5), which are symmetrically arranged on the piston (3).
3. The two-stage variable pressure nitrogen spring according to claim 1, characterized in that: The piston (3) has a first guide ring (13) embedded in its peripheral sidewall, and the first guide ring (13) is slidably connected to the inner sidewall of the inner cavity (7).
4. The two-stage variable pressure nitrogen spring according to claim 3, characterized in that: The number of first sealing rings (10) is at least two, and the first guide ring (13) is located between two adjacent first sealing rings (10).
5. The two-stage variable pressure nitrogen spring according to claim 1, characterized in that: The inner wall of the piston sleeve (9) is fitted with a second sealing ring (15), and the outer wall of the piston rod (2) is in a sealing sliding connection with the inner wall of the second sealing ring (15).
6. The two-stage variable pressure nitrogen spring according to claim 5, characterized in that: The inner wall of the piston sleeve (9) is fitted with a second guide ring (14), the inner wall of the second guide ring (14) is slidably connected to the outer wall of the piston rod (2), and the second guide ring (14) is located below the second sealing ring (15).
7. The two-stage variable pressure nitrogen spring according to claim 6, characterized in that: The inner wall of the piston sleeve (9) is fitted with a dustproof ring (16), and the inner wall of the dustproof ring (16) slides against the outer wall of the piston rod (2). The second sealing ring (15) is located between the dustproof ring (16) and the second guide ring (14).
8. The two-stage variable pressure nitrogen spring according to claim 1, characterized in that: The piston (3) is provided with multiple mounting holes (17), and the flow control valve (4), the upward overflow valve (5) and the downward overflow valve (6) are respectively mounted in the corresponding mounting holes (17).
9. The two-stage variable pressure nitrogen spring according to claim 8, characterized in that: The bottom surface of the piston (3) is equipped with a cover plate (18), and the cover plate (18) has several through holes (19). The outlet of the flow control valve (4) and the inlet of the upward overflow valve (5) are respectively connected to the corresponding through holes (19).
10. The two-stage variable pressure nitrogen spring according to claim 1, characterized in that: The top port of the housing (1) is detachably fitted with a top cover (20), the piston rod (2) slides through the top cover (20), and the top cover (20) encapsulates the piston sleeve (9) in the through hole (8).